diff --git a/llvm/include/llvm/Frontend/OpenACC/ACC.td b/llvm/include/llvm/Frontend/OpenACC/ACC.td
--- a/llvm/include/llvm/Frontend/OpenACC/ACC.td
+++ b/llvm/include/llvm/Frontend/OpenACC/ACC.td
@@ -517,7 +517,6 @@
     VersionedClause<ACCC_Default>,
     VersionedClause<ACCC_Gang>,
     VersionedClause<ACCC_If>,
-    VersionedClause<ACCC_Independent>,
     VersionedClause<ACCC_NumGangs>,
     VersionedClause<ACCC_NumWorkers>,
     VersionedClause<ACCC_Reduction>,
diff --git a/llvm/include/llvm/TableGen/DirectiveEmitter.h b/llvm/include/llvm/TableGen/DirectiveEmitter.h
--- a/llvm/include/llvm/TableGen/DirectiveEmitter.h
+++ b/llvm/include/llvm/TableGen/DirectiveEmitter.h
@@ -73,6 +73,9 @@
 
   bool isDefault() const { return Def->getValueAsBit("isDefault"); }
 
+  // Returns the record name.
+  const StringRef getRecordName() const { return Def->getName(); }
+
 protected:
   const llvm::Record *Def;
 };
diff --git a/llvm/test/TableGen/directive3.td b/llvm/test/TableGen/directive3.td
new file mode 100644
--- /dev/null
+++ b/llvm/test/TableGen/directive3.td
@@ -0,0 +1,30 @@
+// RUN: not llvm-tblgen -gen-directive-decl -I %p/../../include %s 2>&1 | FileCheck -match-full-lines %s
+// RUN: not llvm-tblgen -gen-directive-impl -I %p/../../include %s 2>&1 | FileCheck -match-full-lines %s
+// RUN: not llvm-tblgen -gen-directive-gen -I %p/../../include %s 2>&1 | FileCheck -match-full-lines %s
+
+include "llvm/Frontend/Directive/DirectiveBase.td"
+
+def TestDirectiveLanguage : DirectiveLanguage {
+  let name = "TdlError";
+}
+
+def TDLC_ClauseA : Clause<"clausea"> {
+  let isDefault = 1;
+}
+
+def TDLC_ClauseB : Clause<"clauseb"> {
+}
+
+def TDL_DirA : Directive<"dira"> {
+  let allowedClauses = [
+    VersionedClause<TDLC_ClauseA>,
+    VersionedClause<TDLC_ClauseB>
+  ];
+  let allowedOnceClauses = [
+    VersionedClause<TDLC_ClauseA>
+  ];
+  let isDefault = 1;
+}
+
+// CHECK: error: Clause TDLC_ClauseA already defined on directive TDL_DirA
+// CHECK: error: One or more clauses are defined multiple times on directive TDL_DirA
diff --git a/llvm/utils/TableGen/DirectiveEmitter.cpp b/llvm/utils/TableGen/DirectiveEmitter.cpp
--- a/llvm/utils/TableGen/DirectiveEmitter.cpp
+++ b/llvm/utils/TableGen/DirectiveEmitter.cpp
@@ -111,6 +111,39 @@
   }
 }
 
+bool HasDuplicateClauses(const std::vector<Record *> &Clauses,
+                         const Directive &Directive,
+                         llvm::StringSet<> &CrtClauses) {
+  for (const auto &C : Clauses) {
+    VersionedClause VerClause{C};
+    if (CrtClauses.find(VerClause.getClause().getName()) == CrtClauses.end()) {
+      CrtClauses.insert(VerClause.getClause().getName());
+    } else {
+      PrintError("Clause " + VerClause.getClause().getRecordName() +
+                 " already defined on directive " + Directive.getRecordName());
+      return true;
+    }
+  }
+  return false;
+}
+
+bool HasDuplicateClausesInDirectives(const std::vector<Record *> &Directives) {
+  for (const auto &D : Directives) {
+    Directive Dir{D};
+    llvm::StringSet<> Clauses;
+    if (HasDuplicateClauses(Dir.getAllowedClauses(), Dir, Clauses) ||
+        HasDuplicateClauses(Dir.getAllowedOnceClauses(), Dir, Clauses) ||
+        HasDuplicateClauses(Dir.getAllowedExclusiveClauses(), Dir, Clauses) ||
+        HasDuplicateClauses(Dir.getRequiredClauses(), Dir, Clauses)) {
+      PrintFatalError(
+          "One or more clauses are defined multiple times on directive " +
+          Dir.getRecordName());
+      return true;
+    }
+  }
+  return false;
+}
+
 // Generate the declaration section for the enumeration in the directive
 // language
 void EmitDirectivesDecl(RecordKeeper &Records, raw_ostream &OS) {
@@ -124,6 +157,9 @@
   }
 
   DirectiveLanguage DirLang{DirectiveLanguages[0]};
+  const auto &Directives = Records.getAllDerivedDefinitions("Directive");
+  if (HasDuplicateClausesInDirectives(Directives))
+    return;
 
   OS << "#ifndef LLVM_" << DirLang.getName() << "_INC\n";
   OS << "#define LLVM_" << DirLang.getName() << "_INC\n";
@@ -145,7 +181,6 @@
     OS << "\nLLVM_ENABLE_BITMASK_ENUMS_IN_NAMESPACE();\n";
 
   // Emit Directive enumeration
-  const auto &Directives = Records.getAllDerivedDefinitions("Directive");
   GenerateEnumClass(Directives, OS, "Directive", DirLang.getDirectivePrefix(),
                     DirLang);
 
@@ -615,6 +650,9 @@
   }
 
   const auto &Directives = Records.getAllDerivedDefinitions("Directive");
+  if (HasDuplicateClausesInDirectives(Directives))
+    return;
+
   const auto &Clauses = Records.getAllDerivedDefinitions("Clause");
   DirectiveLanguage DirectiveLanguage{DirectiveLanguages[0]};
   EmitDirectivesFlangImpl(Directives, Clauses, OS, DirectiveLanguage);
@@ -633,6 +671,8 @@
   }
 
   const auto &Directives = Records.getAllDerivedDefinitions("Directive");
+  if (HasDuplicateClausesInDirectives(Directives))
+    return;
 
   DirectiveLanguage DirLang = DirectiveLanguage{DirectiveLanguages[0]};